1. Field of the Invention
This invention relates to the field of fluid inductors and more specifically to the field of fluid inductors primarily intended for use in handling chemical herbicides and pesticides for agricultural use.
2. Background Discussion
Chemical herbicides and pesticides are widely used by farmers throughout the world. In a typical manner of operation, the chemicals are purchased by the farmer in a concentrated form and then diluted in the field just prior to spraying them on the crops.
Handling the concentrated chemicals in the field has always been a problem for the farmer and with the increased toxicity and corrosiveness of today's chemicals, this problem has become one of major concern. This concern is not only for the short term health effects of such exposure including burns and accidental poisoning but also for the long term effects including cancer. For example, a recent study by the National Cancer Institute and University of Kansas reports that farmers who were exposed to herbicides twenty days a year or more were six times more likely to contract certain cancer than people who did not work with such chemicals. This study also reported that the risk to farmers who actually mixed or applied the chemicals increased eightfold.
In one of the most commonly used spraying techniques, the farmer has a large storage or nurse tank of water in the field from which he periodically fills a smaller sprayer tank mounted on a pickup truck. In doing so, the concentrated chemicals are either added directly to the sprayer tank or added to the water as it is pumped from the nurse tank to the truck-mounted sprayer tank. Adding the chemicals directly to the sprayer tank with a hand pump or by manually measuring and dumping the chemicals into the tank are perhaps the oldest and, understandably in view of the health risks, the least popular methods. Further, if a hand pump or any other mechanical pump is used, the additional problem arises that the pump may become contaminated by the chemicals passing through it and become unsuitable for any other use around the farm where the chemical residue may be harmful. In this light, an increasingly popular method of handling the chemicals is to connect a funnel-shaped, graduated tank to the suction side of the water transfer pump between the nurse and sprayer tanks. The graduated tank is typically rather large and need not be filled as often as when the chemicals are added directly into the sprayer tank. Nevertheless, it still must be filled as in the prior methods either by hand or by a separate pump. As in the prior methods, this can result in dangerous exposure to the chemicals and contamination of the pump. Additionally, the graduated tank is typically mounted on the pickup truck with the sprayer tank and because of its relatively large size, it often can be difficult to accurately read the amount of chemicals being dispensed particularly if the truck is not level as commonly is the case in the field.
Another popular method for adding the concentrated chemicals to the water as it flows between the nurse and sprayer tanks is to connect a metered line to the suction side of the pump. The concentrated chemicals are then drawn directly through the meter into the water flow. This direct and continuous feed technique helps avoid potentially harmful exposure to the chemicals but it has several practical drawbacks. For example, the metered line is connected to the suction side of the pump in order to utilize the pump vacuum but in doing so, the chemicals then pass through and contaminate the pump. Additionally, volumetric meters which are very accurate are also very expensive and if cheaper, turbine-style meters are used, accuracy often then becomes a serious problem particularly due to viscosity differences between chemicals and even with the same chemical at different temperatures during the day. Also, turbine-style meters usually have minimum and maximum flow ranges that must be followed thus complicating the overall process and leading to possible operator error.
With these problems in mind, the present invention was developed. With the present invention, concentrated chemicals can be accurately added to the primary water flow downstream of the transfer pump between the nurse and sprayer tanks. In doing so, the chemicals do not pass through the transfer pump and, therefore, do not contaminate it. Further, no additional pump is necessary as the force of the transfer pump is used not only to transfer the water from the nurse tank to the sprayer tank but also to alternately load and unload a graduated or measuring chamber with the concentrated chemical. In addition to this batching manner of operation, the present invention can also be used to continuously inject the concentrated chemicals into the water flow directly from the storage container as well as to back flush water into the storage container for cleaning purposes. In the preferred embodiment, all of these operations can be easily and quickly performed using only the force of the single transfer pump and by manipulation of a single valve.